DS1721

· Temperature measurements require no external components with ±1°C accuracy
· Measures temperatures from -55°C to +125°C; Fahrenheit equivalent is -67°F to +257°F
· Temperature resolution is configurable from 9 to 12 (default) bits (0.5°C to 0.0625°C resolution)
· Maximum conversion time (9-bit resolution) of 150 ms
· Thermostatic settings are user-definable
· Data is read/written via a 2-wire serial interface (open drain I/O lines); 3-bit addressability
· Wide power supply range (2.7V - 5.5V)
· Applications include personal computers, cellular telephones, office equipment, or any thermally sensitive system
· 8-pin, 150-mil SOIC package and 8-pin µSOP package

Voltage on VDD, Relative to Ground ....................-0.3V to +7.0V
Voltage on any other pin, Related to Ground ......-0.3V to +7.0V
Operating Temperature ...................................-55°C to +125°C
Storage Temperature ......................................-55°C to +125°C
Soldering Temperature ............................260°C for 10 seconds

* This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.

The DS1721 2-Wire Digital Thermometer and Thermostat provides 12-bit temperature readings which indicate the temperature of the device. Thermostatic settings and temperature readings are all communicated to/from the DS1721 over a simple 2-wire serial interface. No additional components are required; the device is truly a "temperature-to-digital" converter.

The DS1721 has three address bits that allow a user to multidrop up to eight sensors along the 2-wire bus, greatly simplifying the bussing of distributed temperature sensing networks.

The thermal alarm output, TOUT, is active when the temperature of the device exceeds a user-defined temperature TH. The output of DS1721 remains active until the temperature is equal to or below the user-defined temperature TL, allowing for any hysteresis necessary. The active state of TOUT is configurable by the user.

For applications of DS1721 that require faster conversion times, the user can adjust the readout resolution from 12 to 9 bits, effectively reducing the conversion time from 1.2 s (MAX) to 150 ms (MAX). This is particularly useful in applications where temperature changes large magnitudes very rapidly.

Applications for DS1721 include personal computers/services, cellular telephones, office equipment, or any microprocessor-based, thermally sensitive system.